We propose to investigate a new finding: feeding induced by a long-acting enkephalin analogue injected into the paraventricular nucleus of the hypothalamus. The plan is to repeat our initial finding, then investigate selected aspects of its behavioral, physiological, pharmacological, and neurochemical significance. (1) The effect will be mapped stereotaxically to find the most sensitive brain sites. If the feeding induced at these sites is mediated by opiate receptors, then local injection of the antagonists, naloxone or naltrexone should reverse the effect. The next question will be whether naloxone at these sensitive sites can block natural feeding. (2) The pituitary, adrenals, or pancreas will be removed or blocked to see if any one of them is necessary for opiate-induced feeding. If so, hormone replacement therapy will be used to verify the finding. (3) The interaction of enkephalin with other hypothalamic neurotransmitters, norepinephrine, GABA, and serotonin will be explored. (4) 6-hydroxy-dopamine and radioactive 2-deoxyglucose will be used to begin identifying pathways relevant to opiate-induced feeding. In summary, we will investigate the possibility, suggested by our preliminary results, that endogenous opiates play a role in the control of food intake and body weight.